The present invention is related to an automatic safety gas heating device, more particularly, related to a gas heating device for producing instant hot water.
Conventionally, as the water pressure acts on a diaphram valve of a gas heating device to move a valve rod, the valve rod will not only actuate a microswitch to continue the sparkling of an igniter, but also simultaneously drive a first valve disc to open and admit the gas flowing to the nozzle of a pilot burner, thus igniting the gas thereat. As the pilot flame is produced, a catch which is controlled by a sensor, will be subsequently disengaged from a second valve disc of a gas conduit of the main burner so that the valve rod will subsequently drive the second valve disc to open and admit the gas flowing to the nozzle of the main burner and burning thereat. In such kind of gas heating device, no sooner than the pilot flame or the pilot flame together with the main flame are blown out by the wind, the igniter will re-ignite the gas from the pilot burner, and then fire the main burner as the above-mentioned operation steps. Hence no unburned gas can be permitted to flow out of the nozzle. The valve disc of the main flame will maintain in close state so long as the pilot flame is not able to be ignited. Therefore, in case the igniter fails to work, only a slight amount of the unburned gass will flow out of the nozzle of the pilot burner, thus resulting in a serious problem of suffocation and explosive burning. However, as the main and pilot flames are suddenly blown out by a strong wind, while immediate re-ignition is not available, a large amount of unburned gas will rush out of the nozzle of the main burner and cause explosive burning and suffocation. Moreover, in shortage of electricity the valve disc can not be automatically closed and a great deal of gas will escape from the nozzle of the main burner and pilot burner. Therefore, a further improvement still has to be attempted. In my U.S. patent application Ser. No. 267,349, an automatic safety gas heating device is devised to overcome the above drawbacks. In that device, a valve rod connecting to a diaphram valve does not control valves directly, instead, it merely actuates a microswitch for electric control board. The electric control board, in turn, controls the on-off state of the two solenoid operated valves which are connected in series. Two solenoid operated valves are so oriented that the valves are in closed state when the electric control board runs out of the electricity.
It is attempted in this invention to make safety improvements on the gas heating device specified in U.S. application Ser. No. 267,349, in which a disc valve is additionally provided thereto.
In accordance with the present invention, an automatic safety gas heating device comprises: a valve rod externally connecting to a diaphram valve which is exterted by the pressure of the water; a microswitch for an electric control board, actuated by the movement of the valve rod; a first and a second solenoid operated valves, connected in series, which are separately provided in a first gas conduit communicating with nozzles of a pilot burner and a second gas conduit communicating with nozzles of a main burner, the first and second solenoid operated valves separately actuated by the electric control board; a third valve provided in the first gas conduit and located between the first valve and an upstream of the nozzle of the pilot burner and the second valve, actuated by the movement of the valve rod; an igniter provided near the nozzle of the pilot burner, and actuated by the electric control board; and a first sensor provided in the vicinity of the nozzle of the pilot burner for detecting the presence of a pilot flame and inducing the electric control board to send signals, whereby as the valve rod actuates the microswitch to on condition and the third valve to open, the gas from the pilot burner will start to be ignited while the first valve is actuated to open, immediately after the pilot flame is produced, the sensor will induce the electric control board to send a first electric signal to discontinue the sparkling of the igniter and to open the second solenoid operated valve and supply the gas to the main burner and supply the gas to the main burner and ignited thereat; in the absence of the pilot flame, the sensor will induce the electric control board to send a second electric signal to continue the sparkling of the igniter, and to actuate the second solenoid operated valve and stop the gas supply to the main burner.
In accordance with another aspect of the present invention, the third valve having a valve disc thereof which is thrusted to open by the valve rod against a bias.
In accordance with further aspect of the present invention, in the vicinity of the main burner a temperature detecting sensor is provided for sending a signal to an alarm and simultaneously switching the elcetric control board off when the temperature is beyond a predetermined value.
It is a primary object of the present invention to provide a gas heating device, in which a valve disc is provided for cutting the supply of the gas to the gas burner in case the solenoid operated valve is misguided to open by an erroneous signal from the electric control board.
It is another object of the present invention to provide a gas heating device, in which the overheating of the gas burner can be avoided.
These and other objects will be apparent by illustrating a preferred embodiment with reference to the following drawings, in which: